Techopedia explains IEEE 802.11i

IEEE 802.11i enhances Wired Equivalent Policy (WEP), which was a defacto wireless security standard until it was replaced by the draft version of Wi-Fi Protected Access (WPA). When combined, IEEE 802.11i and WPA 2 form a complete wireless security protocol that includes the Advanced Encryption Standard's (AES) block ciphering technique, four-way handshake and group key handshake for improved authentication and access control.